Motor/Pump Unit

ABSTRACT

A motor/pump unit, in particular for a servo-steering system, includes a pump housing and an intermediate housing. A pump having a first pump shaft is held in the pump housing. The pump housing and the intermediate housing are connected with each other via a flange, and the first pump shaft is mounted in the flange.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage of International Application No. PCT/EP2005/006112 filed Jun. 7, 2005, the disclosures of which are incorporated herein by reference, and which claimed priority to German Patent Application No. 20 2004 009 057.0 filed Jun. 8, 2004, the disclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The invention relates to a motor/pump unit, in particular for a servo-steering system.

Such motor/pump units are used in motor vehicle technology for the provision of auxiliary forces. In addition to assisting the steering force, such a unit can also be used in an active chassis regulation. Generally, a need exists to design the motor/pump units so as to be more compact.

From German Patent Application DE 196 35 411 A1, and corresponding U.S. patent application No. 5,953,391, both of which are incorporated by reference herein, a motor/pump unit comprising a pump housing and an intermediate housing, a pump with a first pump shaft being held in the pump housing, is known. The motor/pump unit includes an electric motor and a single-shaft pump. The motor shaft and the pump shaft are coupled in a central bearing in the intermediate housing.

In German Utility Model DE 299 16 108 U1 a motor/pump unit is shown with a single shaft penetrating the motor housing and the pump housing. On the shaft both the pump rotor and also the runner of the motor are arranged.

It is an object of the invention to provide a compact motor/pump unit which is optimized as regards function but is nevertheless favourably priced.

BRIEF SUMMARY OF THE INVENTION

According to the invention, a motor/pump unit comprises a pump housing and an intermediate housing. A pump having a first pump shaft is held in the pump housing. The pump housing and the intermediate housing are connected with each other via a flange. The first pump shaft is supported in the flange. The support of the pump shaft in the flange, in contrast to a support in the intermediate housing, allows for a very short construction of the pump shaft. Thereby, smaller deviations occur in the truth of rotation, for which reason only relatively simple compensation measures are necessary.

Such a compensation is achieved in particular in that the first pump shaft is supported in a bush which is formed in a housing cover closing the pump housing.

According to the preferred embodiment of the invention, the pump comprises a second pump shaft which is arranged next to the first pump shaft and is likewise supported in the flange. The pump shafts can each be constructed in one piece with a toothed wheel.

The flange is preferably a punched-out plate of an aluminum alloy. To improve the sealing function and the noise damping, the flange is at least partially provided with a NBR (nitrile rubber) coating. The flange size is adapted to the structural conditions of the motor/pump unit and any possible additional functions of the flange (e.g. cooling).

To simplify and improve the centering of the pump housing with respect to the intermediate housing, which hitherto takes place indirectly by means of centering pins provided between the pump housing and the flange and between the flange and the centering housing, it is proposed that at least one centering pin is provided which projects from the pump housing through the flange into the intermediate housing.

A separate motor housing, which would have to be fastened accurately in position on the intermediate housing can be dispensed with, in that an electric motor of the motor/pump unit is held in a section of the intermediate housing.

Other advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, which read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawing, the single FIGURE shows a sectional side view of a motor/pump unit according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The motor/pump unit 10 shown in the FIGURE comprises a housing cover 12, a pump housing 14, an intermediate housing 16 and a housing 18 for a motor, only the motor shaft 28 of which is shown. The stator, rotor, bearing and further details of the motor are not essential for the invention and have been omitted for reasons of clarity.

The pump housing 14 is closed on one end side with the housing cover 12 and connected on the other side with the intermediate housing 16 via a flange 20. One or more centering pins 22, projecting from the pump housing through the flange 20 into the intermediate housing 16 provide for a correct positioning of these three components. In the intermediate housing 16, an inlet and an outlet (not shown) are formed for the fluid which is conveyed in a closed circuit.

The motor shaft 28 is coupled to a first shaft 30 (drive shaft) of a pump held in the pump housing 14. On the drive shaft 30 a first toothed wheel 32 is arranged, which meshes with a second toothed wheel 36 arranged on a second pump shaft 34. The toothed wheels 32, 36 can also be constructed in one piece with the pump shafts 30 and respectively 34. The two pump shafts 30, 34 are each supported on one side in a bush 38 formed in the housing cover 12 and on the other side in the flange 20.

The flange 20 is formed as a punched plate, just as the bushes 38 in the housing cover 12, from an aluminium alloy. To improve the sealing effect and for noise damping, the flange 20 can be coated at corresponding sites with NBR (nitrile rubber).

In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope. 

1. A motor/pump unit, in particular for a servo-steering system, the motor pump unit comprising a pump housing and an intermediate housing, a pump having a first pump shaft being held in the pump housing, the pump housing and the intermediate housing being connected with each other via a flange, the first pump shaft being supported in the flange.
 2. The device according to claim 1, wherein the first pump shaft is also supported in a bush which is formed in a housing cover closing the pump housing.
 3. The device according to claim 1 wherein the pump comprises a second pump shaft which is arranged next to the first pump shaft and is likewise supported in the flange.
 4. The device according to claim 3, wherein the pump shafts are each constructed in one piece with a toothed wheel.
 5. The device according to claim 1, wherein the flange is a punched plate of an aluminium alloy.
 6. The device according to claim 1, wherein the flange is provided at least partially with a NBR (nitrile rubber) coating.
 7. The device according to claim 1, wherein at least one centering pin is provided, which projects from the pump housing through the flange into the intermediate housing.
 8. The device according to claim 1, wherein an electric motor of the motor/pump unit is held in a section of the intermediate housing. 